Hi, I build custom bikes and want to get into painting. I set up a paint room in my shop that uses a 6000cfm fan blowing out the 18" roof vent, I repainted the walls with gloss paint, added lights, fit the door with weatherstripping and turned it into a filter holder that has about 32"x60" of filters. The exhaust pulls through 6 16x25" filters as well. I filtered the shop air through a 3 stage filter/dryer. I am hoping with this setup, I can eliminate contamination coming through the airline, and contamination from dust in the paint area. I'd like to start some basic projects and get feedback on my process so I can become a good painter without as much frustration as it would take just by trial and error.

Welcome to the chaos that is painting..... seems like you are heading down a good road here....just keep digging in and reading threads here as they apply to your latest problems....One thing you might still notice being a problem is contamination from "static electricity" in the air. Combinations of filter media, that air movement, plus the moving air coming from the gun all can generate copious amounts of static which sucks dust to your projects. I work on a lot of fiberglass so it's actually worse for me. If I didn't address it you would see blue arcs jump from my fingertips on panels. Years ago I started attaching ground chains to my chassis and putting them directly to the building ground. Just recently I started using an anti-stat wipedown as my final step. That has helped immensely..... I get almost no air born contamination in my clears.....

I'm doing a test part now, it's fiberglass so the last comment is helpful, I'll see what I can do to ground the part. I'm getting some strange pinholes on the primer layer, so I'm filling them with spot putty.

After filling the pinholes, I sanded the primer to 400 grit and wiped it down with lacquer thinner, then sprayed a nason activated metallic I had left around. I definitely see dust particles sticking to the part despite really carefully filtering the incoming air. Can I scuff this paint layer with a scotch-brite pad to remove the dust hairs and then put on another coat? I want to try mopping down the floor and leaving it a bit damp before shooting another coat.

A big NO NO....never use lacquer thinner for anything but a gun cleaner (and I don't even do that anymore myself). Lacquer thinner can introduce all kinds of "hot" contaminates to your surfaces. They are not virgin materials themselves but recycled solvents. Either just blow off your surfaces as a final or use a good automotive grade tack cloth.....
Not sure on that just adding more base but since you activated it I would think you would be okay.... You are talking base/clear here I assume.....

thanks, I didn't know that about lacquer thinner. I'll keep giving it a go, good thing is the sample parts are cheap since I have a ton of molds haha. So I get to make lots of mistakes without going broke.

That's great....problem on here is guys jump into big projects and end up practicing as they go with us trying to troubleshoot. On that lacquer thinner thing....you especially have to watch fiberglass as the stuff can find it's way into the glass and off gas at much later time. Guy with a Fiero had this really great paint job for about 6 months....then came summer....he had paint bubbles as large as an inch across all over just one section of the car...tracked it back to his son "helping out" with a lacquer thinner rub down of that section....

I needed to use some 800 grit wet to take down the dust bunnies that landed in the paint, the scotchbrite pad wasn't aggressive enough, so I did that, washed it down, dried it, blew it off, wiped it down with a tack cloth, then reshot. I also wet mopped the floor prior to, and blew the room down with the compressor gun. The results seem better, there were 2-3 little dust bunnies on the top of the part, and I also noticed what looked like paint buildup on the gun nozzle, maybe the dust was actually broken off chips of this? I'm just using a husky touchup gun now, so I know it's crap, I don't know enough about what makes a good gun to invest in a few yet.

themotoworks wrote:I I'm getting some strange pinholes on the primer layer, so I'm filling them with spot putty.

im thinkin that might not be a good thing to do for pinholes. there could be problems with contamination that could come back down the road.
im justa greenhorn hobbiest,though. one of the pros might be able to correct me if im not right.

what spot putting are you using?

Dust nibs are a fact of life. They happen in the best full downdraught booths, they even happen in the factory with full clean rooms and robots instead of painters. In most shops, just as in the factory, dealing with the inevitable then determines the quality of finish.

You can use a tungsten block, a nib file or various kinds of abrasive but the end result is that you reduce the lump to the height of the rest of the paint and it essentially disappears. I like to use a 3" Trizact pad in P2000, then P3000 on a small DA and then buff. Works well for me.

Pinholes are also a fact of life, regardless of how hard we try to avoid them. Usually start in the filler but don't always become visible until after priming. I use powder guide coat to help make them visible in the filler and then use a fine filler to fill them up before priming. My preference is Cromax 769R which is very fine but not as liquid as some of the glazes. There are others out there but all the good ones use a catalyst to make the hardening process complete. There are 1K products out there too, much cheaper but the issue is that they can (and do) shrink, leaving a hole still in the surface.

themotoworks wrote: I also noticed what looked like paint buildup on the gun nozzle, maybe the dust was actually broken off chips of this?

Absolutely. Even the top shelf Devilbiss guns have a bad habit of getting a buildup in the neck of the gun wheich dries and then gets flushed out as little lumps during a subsequent job. Cleaning your gun, properly, is absolutely essential.

Agin on dust, most actually comes from you. Clothes that have fibres, tiny flakes of skin, hair, dirt and oils. Make sure you wear a full paintsuit when painting so you're covered top to toe. It really does make a difference.